If you're looking for evidence of Andrzej Wajda's filmmaking smarts, it's right there in his first, black-and-white movie, made in 1955. A trench-coated young man races through Warsaw at the height of World War II, past corpses dangling from streetlights, pursued by Nazi soldiers who chase him into a building and up a central staircase.

Over the next two weeks, Republicans and Democrats will gather in Cleveland and Philadelphia for a ritual that has become almost entirely ceremonial: Each party will "select" pre-selected presidential candidates.